1. Field of the Invention
The present process is directed to an improved utilization of zerovalent nickel complexes which are employed as catalysts for the production of dinitriles. More particularly, the present invention is directed to the recovery and recycle of nickel catalyst to thereby minimize loss of elemental nickel and optimize the production of a catalyst having a low ligand to nickel ratio.
2. Description of the Prior Art
U.S. Pat. No. 4,385,007 issued on May 24, 1983 discloses an improved process for the preparation of zerovalent nickel-organophosphorus ligand containing catalysts which are employed in the hydrocyanation reaction, which disclosure is incorporated herein by this reference.
U.S. Pat. No. 3,496,218 issued Feb. 17, 1970; U.S. Pat. No. 3,766,237 issued on Oct. 16, 1973; U.S. Pat. No. 3,903,120 issued on Sept. 2, 1975 and U.S. Pat. No. 3,773,809 issued on Nov. 20, 1973 disclose the general process conditions for catalyst preparation and product recovery to which the present invention can be applied.
U.S. Pat. No. 4,416,825 issued Nov. 22, 1983 discloses a continuous process for the preparation of zerovalent nickel complexes with organic phosphorus compounds, the product of which can be blended with the product of the present process.
The process of the present invention is especially effective in obtaining catalysts such as those used in the process described in U.S. Pat. No. 4,371,474 issued on Feb. 1, 1983, the disclosure of which is incorporated herein by this reference.